Mapping barley leaf stripe resistence in Tibetan hulless barley based on BSR-seq and Iso-seq

Barley leaf stripe (BLS) is a common fungal disease caused by P yrenophora graminea in hulless barley (Qingke). Once leaf stripe occurs, it will seriously affect the yield and quality of Qingke.

This study utilized the disease-resistant variety Kunlun14 (KL14) and the susceptible variety Z1141 as materials to analyze the changes in the disease index, soluble protein content, relative conductivity, proline (Pro) content, malondialdehyde (MDA) content, and chlorophyll content (CC) in leaves before and after infection with barley leaf stripe (BLS), which is caused by P. graminea. After infection, both the disease incidence and severity in the Z1141 group were significantly higher than those in the KL14 group. BSR-seq analysis was performed on the resistant and susceptible bulks derived from the parents and the F₂ population (Z1141 × KL14), and three candidate regions were identified: one locus (648,449,784 base pairs (bp)) and one interval (659.7-668.0 Mb) on chromosome 5H, and one interval (12.1-16.3 Mb) on chromosome 6H. A total of 3,126 differentially expressed genes (DEGs) were identified by Isoform sequencing (Iso-seq) using leaves of KL14 and Z1141 before and after P. graminea infection. An integrated analysis of BSR-seq and Iso-seq data, supplemented by qRT-PCR validation and functional annotation, pinpointed HvWAK and HvRGA as candidate genes for BLS resistance. Expression analysis demonstrated that the expression levels of both genes peaked at the week seven following P. graminea infection, and the timing of transcriptional activation in Z1141 preceded that in KL14.

This study analyzed the resistance mechanisms of Qingke against P. graminea through both physiological response analysis and identification of disease resistance genes. The results of this study not only contribute to a deeper understanding of plant-pathogen interaction mechanisms but also establish a valuable genetic resource base for molecular marker-assisted breeding of BLS-resistant Qingke and the functional characterization of the key candidate genes HvWAK and HvRGA.